This description relates generally to inkjet printing technology which is used in a new nonconventional environment, here for color mixing in airbrush painting. Here we are dealing with a marriage of two, previously distinct technologies, which now yields several new patentable concepts. Before delving into a detailed description of these new concepts, a brief discussion of conventional inkjet technology may be helpful, along with some of the difficulties encountered with conventional airbrush technology.
Conventional inkjet printing mechanisms use cartridges, often called xe2x80x9cpens,xe2x80x9d which shoot drops of liquid colorant, referred to generally herein as xe2x80x9cink,xe2x80x9d onto a page. Each cartridge has a printhead formed with very small nozzles through which the ink drops are fired. Most often, the printhead is held in a carriage that slides back and forth along a guide rod in a xe2x80x9creciprocating printheadxe2x80x9d system, with the page being advanced in steps between each pass of the printhead. To print an image on paper media, for instance, the printhead is propelled back and forth across the page, shooting drops of ink in a desired pattern as it moves. Other printing systems, known as xe2x80x9cpage-wide arrayxe2x80x9d printers, extend the printhead across the entire page in a stationary location and print as the media advances under the printhead. The particular ink ejection mechanism within either type of printhead may take on a variety of different forms known to those skilled in the art, such as those using piezo-electric or thermal printhead technology.
For instance, two earlier thermal ink ejection mechanisms are shown in U.S. Pat. Nos. 5,278,584 and 4,683,481, both assigned to the present assignee, the Hewlett-Packard Company. In a thermal system, a barrier layer containing ink channels and vaporization chambers is located between a nozzle orifice plate and a substrate layer. This substrate layer typically contains linear arrays of heater elements, such as resistors, which are energized to heat ink within the vaporization chambers. Upon heating, an ink droplet is ejected from a nozzle associated with the energized resistor. By selectively energizing the resistors as the printhead moves across the page, the ink is expelled in a pattern on the print media to form a desired image (e.g., picture, chart or text).
Colors typically dispensed by the cartridges are black, cyan, yellow and magenta, with the resulting image color being obtained by mixing these four colors when the ink droplets impact the page. Recently, an imaging cartridge system has been introduced by the Hewlett-Packard Company of Palo Alto, Calif., as the DeskJet(copyright) 693C model inkjet printer. This is a two-pen printer which uses a tri-color cartridge, carrying full dye-loads of cyan, magenta and yellow, and a black cartridge which may be replaced with a tri-color imaging cartridge. This imaging cartridge carries reduced dye-load concentrations of some colors, such as cyan and magenta, along with a full or partial dye-load concentration of black ink. The imaging cartridge allows the printer to produce more continuous tone changes, particularly flesh tones, so the resulting image has near-photographic quality, with very little graininess. In the same vein, inkjet cartridges may be produced to carry custom colors, such as specialized tones having trademark notarization.
Turning now to airbrush technology, there are a variety of different styles and types of conventional airbrushes sold at most typical hobby stores. These handheld airbrushes are used for painting models, crafts, fingernails, pictures, automobiles, motorcycles, T-shirts, etc. A variety of different paint compositions may be used in these airbrushes, such as lacquers, inks, watercolors, thinned solvent-based enamels, airbrush acrylics, and the like. Typical airbrushes use compressed air to draw the fluid from a reservoir into a nozzle where the fluid is atomized and propelled onto a surface to create an image.
For projects requiring multiple colors, the conventional airbrush painter has several options as to how to proceed. One way to apply multiple colors is to prepare each color separately, spray it on the image, and then clean the airbrush before moving on to apply the next color. Unfortunately, the process of switching from one color to another is time consuming and messy, because the airbrush must be completely cleaned between colors. Indeed, mixing, trying and tuning in the colors is time consuming and costly in terms of wasted ink while trying to obtain the desired color mix. Another option for applying multiple colors is for the painter to use multiple airbrushes each carrying a single color. Unfortunately this option has its drawbacks, too, due to the added cost of purchasing multiple airbrushes, and because each of these airbrushes now must be cleaned at the completion of the paint job. A further drawback of these earlier systems is that the finished image is limited to having only the exact color and hue of the paint which is loaded in the airbrush.
One goal herein is to provide a new inkjet airbrush system and method which expands the concepts of inkjet printing to other uses, such as for painting artwork and other images on items like canvas, sculptures, murals, models, vehicles, etc.